PHILADELPHIA — Florida Gulf Coast went from shocking the college basketball world to downright impressing it. And the Eagles were smiling the whole time.

Playing loose and easy, little-known FCGU beat San Diego State 81-71 on Sunday to become the first No. 15 seed to reach the Sweet 16 of the NCAA tournament.

“We don’t take ourselves too seriously,” said FloridaGulfCoast coach Andy Enfield, whose players tossed him in the air and poured water on him in raucous celebration before his postgame interviews. “We try to have fun, get serious when we have to.

“Our goal was to make history and we did it.”

The next opponent for the upstart state school will be the main campus, third-seeded Florida, on Friday night in the South Regional semifinal in Dallas.

“We tried to scrimmage them early in the season in the preseason, now we get our shot,” Enfield said.

Bernard Thompson had 23 points and Sherwood Brown added 17 for FGCU, the 16-year-old school in just its second season being eligible for postseason play.

In its first-ever NCAA tournament game on Friday, the Atlantic Sun champion busted brackets everywhere with an upset win over No. 2 Georgetown, a game the Eagles took control of with a 21-2 run in the second half.

It went much the same way against San Diego State.

This time the run was 17-0 and Brown, who was saddled early in the second half with foul trouble, had eight of the first 10 points of it. When it was over the Eagles led 71-52 with 4:19 to play and the only decisions left were how the players and fans were going to celebrate.

After at least one basket, Brown opened his mouth and waggled his tongue at FCGU as he ran up court.

And after the game, the whole team joined in a bird dance that the players on the bench.

On the court, FCGU played like it had nothing to lose. And really, the Eagles didn’t. Given their school’s short history, nobody expected them to win a game at the NCAA tournament, let alone two.

Brett Comer, who didn’t have as many lob passes for dunks as he did against the Hoyas, finished with 10 points and 14 assists, some of which resulted in dunks that had the crowd cheering and wanting more.

FGCU even unleashed another offensive weapon. Christophe Varidel, a native of Switzerland, hit two big 3s early for the Eagles and finished with 11 points after going scoreless against Georgetown.